1. Technical Field
This invention relates generally to a releasable latch for maintaining a cover in fixed relationship with a housing, and more particularly, to such a latch that is biased toward an engaged position by torsionally applied forces.
2. Background Art
Latch mechanisms are commonly used to secure a cover over a compartment, and several different latch mechanisms have been proposed for such purposes. Generally, latch mechanisms can be divided into two categories. The first group relies on a spring, or equivalent, compressible member, to provide the latching force in combination with a button arrangement. This type of latch generally exhibits excellent dependability, durability, and feel. However, they are also relatively costly and have space requirements which often exceed the room allowable. The second group relies on the ductility of the latch material itself to provide the latching force. The second group of latches are typically based on a cantilever beam arrangement, either as an end-loaded beam with one end fixed, or a center-loaded beam with both ends fixed. Such arrangements are generally more cost effective and space efficient than latches having separate compressible spring elements. However, the durability, dependability, and feel are not as good, and the useful service life of cantilevered beam arrangements is highly dependent on the design configuration, material properties, and operating environment.
Thus, current latch designs generally are either costly and require a considerable amount of space, or have limited durability, dependability, and operability. Though the end loaded, one-end fixed, cantilever configuration is used in a variety of applications, space limitations make this design particularly susceptible to fatigue failure. In addition, environmental conditions such as excessively high or low temperatures, the presence of skin oils and the like, further reduces fatigue life. Subsequently, the tactile feel of the latch is compromised as a result of trying to improve durability.
The above problems are particularly conspicuous when the latches are arranged on relatively small instruments, such as portable telephones, cellular phones and similar telecommunication equipment. Such instruments typically have battery compartments which are separable from the housing for recharge purposes. The battery compartments typically include an outer cover that is integrally shaped with the transceiver housing of the instrument.
The above invention is directed to overcoming the problems set forth above. It is desirable to have a latch arrangement that is durable, has excellent feel for enhanced operability, and is economical to produce. It is also desirable to have such a latch arrangement that is space efficient and has a remotely positioned member which does not normally come in contact with an operator's skin, and provides a bias force sufficient to maintain a cover at a desired position with respect to a housing. Such an arrangement reduces the amount of skin oils and other hand-carried substances that are deposited on the stressed member, and the resultant adverse affects of such materials on the fatigue characteristics of the member.